How does MySQL modify indexes in a table structure?

You can add or delete indexes to or from a table structure in MySQL. The following describes how to modify the table structure in MySQL for your reference.

Modify Table Structure in MySQL -- add an index

Mysql> alter table tablename change depno int (5) not null;
Mysql> alter table tablename add index name (field name 1 [, field name 2…]);
Mysql> alter table tablename add index emp_name (name );

Modify Table Structure in MySQL -- index with primary keywords

Mysql> alter table tablename add primary key (id );

Add an index with unique conditions

Mysql> alter table tablename add unique emp_name2 (cardnumber );

Delete An index

Mysql> alter table tablename drop index emp_name;

Modify Table:

Add field:

Mysql> alter table table_name ADD field_name field_type;

Modify the original field name and type:

Mysql> alter table table_name CHANGE old_field_name new_field_name field_type;

Delete field:

Mysql> alter table table_name DROP field_name;

10 common MySQL command lines

Back up the MySQL command line of the database

Seven common MySQL command lines

How to view MySQL user permissions

MySQL permission table Introduction